[Astronomy seminar] Astronomy Department Seminar - March 14th David Sobral

[Astronomy seminar announcements]

On Friday, March 18th at 10:30 we have our next seminar with David 
Sobral (Lancaster) speaking via Zoom

*Resolving the formation and evolution of primeval galaxies: from 
re-ionisation to cosmic noon*

I will present new results that reveal the nature and evolution of 
primeval galaxies, picked up in large and deep surveys due to their 
Lyman-alpha emission. I will show how Lyman-alpha emitters (LAEs) are 
an incredibly rare population of galaxies in the local Universe, but 
become dominant into the epoch of re-ionisation and that they have the 
properties and the number density necessary to dominate and drive 
cosmic re-ionisation.

Lyman-α (Lyα) is intrinsically the brightest line emitted from active 
galaxies, but its resonant nature and susceptibility to dust as a 
rest-frame UV photon makes Lyα very hard to interpret due to the 
uncertain Lyα escape fraction, until now. By conducting large blind 
surveys at different cosmic times and the necessary spectroscopic 
follow-up, we have obtained a simple empirical relation that robustly 
retrieves the Lyα escape fraction as a function of Lyα rest-frame EW. We 
show that the relation constrains a well-defined anti-correlation 
between ionisation efficiency and dust extinction in Lyman-alpha 
emitters (LAEs) which is likely an evolutionary sequence for very young 
metal poor sources going through a LAE phase. We also reveal how those 
LAEs/primeval galaxies have high escape fractions of not just 
Lyman-alpha photons, but also LyC, and how the production and escape 
seem to be linked together.

We are trying something new this year with leaving the Zoom call open 
after the formal hour of the seminar is up to allow the speaker, if they 
wish, to chat informally with anyone who is interested.

Thanks
Chris and Carolina

Christopher Usher is inviting you to a scheduled Zoom meeting.

Topic: Astronomy Department Seminar - David Sobral
Time: Mar 18, 2022 10:30 AM Stockholm

Join Zoom Meeting
https://stockholmuniversity.zoom.us/j/64177331893?pwd=bzRRT3BjTFZtVDdnL08rdlg1VEpUQT09 


Meeting ID: 641 7733 1893
Passcode: eSPORdIpAR
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